Administering drugs within the framework of “convection-enhanced delivery” (CED) is a neurosurgical application in which a catheter has to be inserted into solid brain tissue. A drug is administered very slowly through the catheter into the brain tissue. A syringe is provided for conveying the drug, wherein this term is to be understood here to very generally mean any devices which output a drug (for example, using a piston) from a depot. The syringe comprises a piston advancing device or pump device or is connected to such a device. Using this device, a certain amount of drug per time segment is mechanically and preferably automatically injected into a catheter supply line, and in most cases, this sets a constant flow rate over a number of days.
Conventional CED drug supply systems thus comprise a direct drug line from the syringe to the catheter; the conveying pressure is transferred directly onto the drug by the conveying device (syringe).
The problem with these conventional supply systems is that the drug fluid system has to be opened if the supply is to be manipulated. However, manipulations are sometimes necessary, for example if a new, refilled syringe is to be connected, or if the patient has to be separated from the supply system, in order for example to undergo a CT or MR scan. Opening the drug fluid system can cause contamination or allow air to enter the drug lines.